We perform first principles total energy calculations to study the
adsorption and diffusion of B and Al on GaN (0001) and (000-1)
surfaces, in
the (2x2) and ($\surd $3x$\surd $3) periodicities. Studies are
done within
the periodic density functional theory. In the repeated slab
geometry
method, the slab of the GaN(0001) surface is formed by 4 and 5
bilayers, for
the (2x2) and ($\surd $3x$\surd $3) periodicities, respectively.
The slab of
the GaN(000-1) surface is formed by 3 and 4 bilayers, plus a Ga
monolayer
for the (2x2) and ($\surd $3x$\surd $3) periodicities, respectively.
Dangling bonds of the bottom surfaces are saturated by
pseudo-hydrogen
atoms. The two lowest bilayers and the hydrogen are frozen at
their ideal
positions to simulate the bulk like environment. The upper
bilayers and the
adsorbed atoms are set free to relax. For the high symmetry sites
the most
stable structure of the adsorption on the GaN(0001)-(2x2) surface
is the
T4-site. For the adsorption on the GaN(000-1)-(2x2) is H3.

*Conacyt grant 48549, DGAPA grant IN101809 and VIEP-BUAP.

To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2010.MAR.D9.6